Abstract 12095: Echocardiographic Assessment of Chamber Stiffness - Contrasting Normal Sinus Rhythm and Chronic Atrial Fibrillation

Abstract

Echocardiographic diastolic function (DF) assessment remains a challenge in atrial fibrillation (AF), because indexes such as E/A cannot be used and because chronic, rate controlled AF causes chamber remodeling. To determine if echocardiography can accurately characterize diastolic chamber properties we compared 14 AF subjects to 24 normal sinus rhythm (NSR) subjects undergoing simultaneous echocardiography-cardiac catheterization (417 beats analyzed). Conventional DF parameters (DT, E_peak, AT, E_dur, E-VTI, E/E′) and novel E-wave derived, kinematic modeling based parameter specific for chamber stiffness (k), were compared. For validation, chamber stiffness (dP/dV) was independently determined from simultaneous, multi-beat P-V loop data. Results show that neither AT, E_peak nor E-VTI differentiated between groups. Although DT, E_dur and E/E’ did differentiate between groups (DT_NSR vs. DT_AF p<0.001, E_durNSR vs. E_durAF p<0.005, E/E′_NSR vs. E/E′_AF p<0.05), the model derived chamber stiffness parameter k was the only parameter specific for chamber stiffness, (k_NSR vs. k_AF p<0.005). The invasive gold-standard, end-diastolic stiffness in NSR was indistinguishable from end-diastolic (i.e. diastatic) stiffness in AF (p=0.57). Importantly, the analysis provided mechanistic insight by showing that diastatic stiffness in AF was significantly greater than diastatic stiffness in NSR (p<0.005). We conclude that passive (diastatic) chamber stiffness is increased in chronic, rate controlled AF hearts relative to NSR controls and that in addition to DT, the E-wave derived, chamber stiffness specific index k, differentiates between AF vs. NSR groups, even when invasively determined end-diastolic chamber stiffness fails to do so.